Plague Bug Wasn't all that FierceThe article discusses research published in the journal "Nature" by geneticists and anthropologists including Hendrik Poinar in which samples of Yersinia pestis, the bacteria which caused the Black Death, which were taken from exhumed plague victims were analyzed. The scientists found that the bacteria had no genetic mutations which would have made it more virulent and suggest that other factors such as climate, malnourishment, and stress made the disease lethal.